Communication and data transmission systems utilizing transmission lines of various lengths have inherent problems. For example, a long transmission line can cause pulse distortion and/or intersymbol interference between data bits which will result in an erroneous signal transmission. Such a condition is typically corrected by the use of an equalizer to restore the signals or pulses transmitted, however, the use of such a device requires matching the frequency characteristics of the device with the frequency characteristics of a specific length of transmission line employed. If a wide range of cable lengths is involved, such as from 0 to 5000 feet, the cable response time can vary from a subnanosecond to 1.5 microseconds and the equalizer must be adjusted to match each different length of transmission line. Alternatively, a plurality of equalizers, each designed for a different range of transmission line lengths, can be provided and selectively switched into the system to accomplish this matching. Another approach utilized by the prior art is the use of delay lines to "build-out" short transmission lines to a range of cable lengths for matching with an equalizer adjusted to this range of cable lengths. All of these approaches involve additional expensive components and/or are time-consuming and cumbersome to effect.
Because of this, it has become desirable to develop a circuit arrangement that can be used to match a wide range of transmission line lengths with an equalizer so that re-adjustment of the equalizer is not necessary for each length of transmission line employed or for each sudden change in transmission line length which can occur in multistation communication systems.